06/09/2023
Biot-Savart law and the theorem on the circulation of the magnetic induction vector
In 1820, French scientists Jean Baptiste Biot and Felix Savard, in the course of joint experiments on the study of magnetic fields of direct currents, unequivocally established that the magnetic induction of the current flowing through a conductor of direct current can be considered the result of the general action of all sections of this conductor with current. This means that the magnetic field obeys the principle of superposition (the principle of superposition of fields).

The magnetic field created by a group of conductors with direct current has such a magnetic induction that its value is determined as the vector sum of the magnetic inductions created by each conductor individually. That is, the induction B of a conductor with direct current can be fairly represented by the vector sum of elementary inductions dB belonging to the elementary sections dl of the conductor under consideration with direct current I.

It is practically impossible to single out an elementary section of a conductor with direct current, because direct current is always closed. But you can measure the total magnetic induction created by the conductor, that is, generated by all the elementary pieces of this conductor.
Thus, the Bio-Sovar Law allows you to find the value of the magnetic induction B from a section (of a known length dl) of a conductor, with a given direct current I, at a certain distance r from this section of the conductor and in a certain direction of observation from the selected section (given through the sine of the angle between the direction of the current and the direction from the section of the conductor to the investigated point in space near the conductor):
It has been experimentally established that the direction of the magnetic induction vector is easily determined by the rule of the right screw or gimlet: if the direction of the translational movement of the gimlet du
